Lube oil pump with relief valve

Abstract

An oil pump has a split frame with the pump mechanism situated in a chamber in one of the frames or between the split frames. An inlet conduit extends from an inlet port to the low pressure side of the pump and an outlet conduit extends from the high pressure side of the pump to an outlet port. An excess pressure relief path is provided to permit fluid flow from the outlet conduit to the inlet conduit when the outlet conduit pressure exceeds the inlet conduit pressure by a predetermined difference. This is accomplished by providing a bypass channel formed in one frame and fluidly intersecting the outlet conduit, and a valve cavity formed in the other frame and fluidly intersecting the bypass channel and the inlet conduit. Valve means are situated in the valve cavity for isolating the bypass channel from the inlet conduit during normal pressure differences between the inlet and outlet conduits. Upon the occurrence of excess pressure in the outlet conduit, the valve opens to permit fluid flow from the outlet conduit to the inlet conduit.

We claim: 
     
       1. In an oil pump of the type having a split frame with a pump mechanism situated in a chamber formed between the split frames, an inlet conduit extending from an inlet port to the low pressure side of the pump mechanism and an outlet conduit extending from the high pressure side of the pump mechanism to an outlet port, the improvement comprising an excess pressure relief path including: a bypass channel integrally formed within one frame and fluidly intersecting the outlet conduit; U.S. Ser. No. 319,167   a relief orifice integrally formed in the other frame and situated between the bypass channel and the inlet conduit;   a valve cavity integrally formed within said other frame and fluidly connected between the bypass channel and the relief orifice such that the pressure relief flow path includes said valve cavity; and   valve means situated within aid valve cavity, for isolating the bypass channel from the inlet conduit during normal pressure differences between the inlet and outlet conduits, but passively initiating fluid flow from the bypass channel to the inlet conduit when the outlet conduit pressure exceeds the inlet conduit pressure by a predetermined difference.   
     
     
       2. The oil pump of claim 1, wherein the valve means includes a valve member having a substantially flat head and means for biasing the valve member head into contact against a flat portion of the one frame to close the bypass channel. 
     
     
       3. The oil pump of claim 2, wherein the bypass channel includes a fluid pocket having a pocket opening defined by a rim in the one frame;   the valve cavity has a cavity opening in the other frame in confronting relation with the pocket opening, the cavity opening having a larger cross-sectional area than the pocket opening; and   the head of the valve member has a cross-sectional area larger than the pocket opening area but smaller than the cavity opening cross-sectional area.   
     
     
       4. A lube oil pump comprising: a first frame member having a front face, a substantially solid first end portion, and a cut out rear face;   a second frame member having a front face, a rear face, and a substantially solid second end portion, the front face of the second frame member sealingly engaging the rear face of the first frame member, whereby said cut out defines a pump chamber between the frame members and said end portions have respective first and second surfaces in juxtaposed sealed relation; U.S. Ser. No. 319,167   a pump mechanism situated within the pump chamber, having a first configuration in use defining a low pressure pocket and a second configuration in use defining a high pressure pocket;   an inlet conduit leading from one of said end portions through both of said frame members into said low pressure pocket;   an outlet conduit leading from said high pressure pocket through both of said frame members to said one end portion;   a bypass channel integrally formed as a cut out in said juxtaposed surface in the other of said end portions, in fluid communication with the outlet conduit;   a valve cavity integrally formed within said first end portion adjacent said inlet conduit, the valve cavity being in fluid communication with the bypass channel and the inlet conduit;   valve means seated within the valve cavity and biased against the other end portion to close the cavity from the bypass channel unless the fluid pressure in the bypass channel exceeds a threshold pressure, whereupon the valve means opens and relieves the bypass channel pressure into said inlet conduit.   
     
     
       5. The oil pump of claim 4, wherein the inlet and outlet conduits are oriented substantially parallel to each other, and the bypass channel is oriented substantially transversely to the conduits. 
     
     
       6. The oil pump of claim 4, wherein the bypass channel includes rim means defining an aperture in juxtaposed alignment with the valve cavity, and wherein said valve means is biased against said rim means when the valve means is in the closed position.